1. Possibly free the jammed door by taking a pen, or metal letter opener (or that 16d nail you've got secreted in your desk) and removing the hinge pins, using your shoe or other implement as a hammer.

2. If your interior office walls are constructed of drywall, or other penetrable material, use your stapler, or your shoe ? or your fist if you're feeling macho ? to punch a couple of 4-inch or so staggered holes in the wall, up to the ceiling. Four or so holes should do it. The idea being to create hand- and foot-holds to climb the remaining few feet to the ceiling (after standing on your chair, or inverted wastebasket, which will get you started a few feet off the ground).

This would work best if the holes were located alternating on either side of one of the (presumably) metal studs, located by tapping wall with fist. Just to be on safe side, avoid locations/studs in-line with electrical wall outlets.

This is where that time spent on the climbing-wall at your health club pays dividends. <img src="/images/graemlins/grin.gif" alt="" />

Edit: It occurs to me, too, that if your walls are easily penetrable (drywall etc), you could simply (?) use your chair or other improvised tool to nibble a 2-ft. or so hole in the wall, through to the outer hallway, or adjoining room.